The need is known of having available a generator of reference voltage capable of tracking with a high degree of accuracy the voltage drop across a resistance in a temperature interval ranging from -40.degree. C. to +150.degree. C.
As is known, the voltage drop across a resistance is normally used in a control circuit of a load current, wherein there is a comparator which at one input is supplied with a reference voltage and at the other input is supplied with a voltage present across a sensing resistance arranged in series with the load with the interposition of a switch. A control circuit operated by the output of the comparator opens the switch every time the voltage across the sensing resistance is higher than the reference voltage, making it thus possible to control the current flowing through the load.
It is important to have a generator of reference voltage having a heat coefficient that is the same as that of the sensing resistance, so that it is possible to read and control the value of the current in the load with the same degree of accuracy at all temperatures.
This is obtained, for example, with the generator described in the Italian Patent Application No. 22470 A/90 filed on Dec. 21, 1990 and corresponding U.S. patent application Ser. No. 07/811,261, filed on Dec. 19, 1991.